Electrodes with solid polymer electrolytes and reduced porosity

Abstract

An electrode/electrolyte assembly that has a well-integrated interface between an electrode and a solid polymer electrolyte film, which provides continuous, ionically-conducting and electronically insulating paths between the films is provided. A slurry is made containing active electrolyte material, a liquefied, ionically-conductive first polymer electrolyte with dissolved lithium salt, and conductive additive. The binder may have been liquefied by dissolving in a volatile solvent or by melting. The slurry is cast or extruded as a thin film and dried or cooled to form an electrode layer that has some inherent porosity. A liquefied second polymer electrolyte that includes a salt is cast over the electrode film. Some of the liquefied second polymer electrolyte fills at least some of the pores in the electrode film and the rest forms an electrolyte layer on top of the electrode film. After solidifying by either drying or cooling, the dual-cast electrode assembly includes both an electrode with low porosity and an adjacent solid polymer electrolyte film. A lithium secondary battery that employs the novel electrode assembly is also provided.